Power Meter
R&S
®
Cable Rider ZPH
138
User Manual 1321.0950.02 ─ 03
8.1.2 Performing and Configuring Measurements
After you have connected a power sensor, the R&S Cable Rider ZPH immediately
starts to measure the signal power.
Defining the center frequency
Power sensors have a memory containing correction values that are dependent on the
frequency. Hence, measurement results are the most accurate for signals whose fre-
quency you know.
Note that the R&S Cable Rider ZPH maintains the center frequency that you have set
in another operating mode. In that case, it uses that frequency as the power sensor fre-
quency.
If you want to perform measurements on another known signal, you can change the
power sensor frequency manually.
1. Select the "Freq" softkey.
The R&S Cable Rider ZPH opens an input field to define the frequency opens.
2. Enter the frequency of the signal.
The R&S Cable Rider ZPH transfers the new frequency to the power sensor which
then corrects the measured power readings.
Zeroing the power sensor
Offset voltages and currents have most effect on the power readout when measuring
low powers. You can compensate for these offsets by zeroing the power sensor.
Do not apply power during the zeroing process, as the power sensor cannot distinguish
between external powers and internal offsets.
1. Select the "Zero" softkey.
2. The R&S Cable Rider ZPH asks you not to apply any signals to the power sensor
during the zeroing process.
3. Disconnect the power sensor from any signal sources.
4. Select the "Continue" softkey to start zeroing.
5. Select "Cancel" softkey to abort zeroing, for example, if you cannot disconnect the
signal source.
The R&S Cable Rider ZPH immediately starts power sensor zeroing.
While zeroing is in progress, the R&S Cable Rider ZPH shows the message “Zero-
ing power sensor, please wait while the system is zeroing the power sensor”.
Using a Power Sensor
